FETAL CMV INFECTION: ROLE OF THE HUMAN PLACENTA

胎儿 CMV 感染：人胎盘的作用

• 批准号: 6497306
• 负责人: LENORE PALMA PEREIRA
• 金额: $ 27.31万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6497306
• 关键词: Herpesviridae disease; cell differentiation; cell migration; clinical research; cytomegalovirus; female; human pregnant subject; human tissue; placenta; placental transfer; pregnancy infection; trophoblast; vertical transmission; virus genetics; virus infection mechanism

Human cytomegalovirus (CMV) infection of the embryo/fetus is the leading cause of congenital viral infection. It occurs in 1 percent of live births in the United States. The consequences include poor neurologic development, visual impairment, and sensorineural hearing loss. Placentas from women with congenital CMV who abort spontaneously (15 percent) show evidence of infection without fetal involvement, indicating that placental infection precedes virus transmission to the fetus. Successful pregnancy depends on normal placental development, a stepwise process that involves differentiation of the organ's epithelial stem cells, termed cytotrophoblasts (CTBs). CTBs differentiate via two pathways into villi that either anchor the placenta to the uterine wall or float in maternal blood. In the first pathway, CTBs in anchoring villi switch on expression of adhesion receptors and proteinases that are needed for invasion of maternal arteries, as well as immune molecules that elicit maternal tolerance. Our studies showed that CMV infection of first trimester differentiating/invading CTBs in vitro downregulates expression of two functionally important stage-specific antigens nonclassical MHC class Ib HLA-G and integrin alpha1beta1. Moreover, the invasion competence of infected CTBs in vitro was dramatically impaired as was the 2invasiveness of CTBs isolated from a placenta infected with CMV in vivo. This correlation between impaired invasion and disregulation of alpha1beta1 suggests that faulty invasion of maternal arteries may be a hallmark of CMV-infected placentas. In the second pathway, CTBs fuse to form syncytiotrophoblasts (STBs) that cover floating villi. When floating villi were exposed to CMV in vitro, STBs were uninfected and the underlying CTB stem cells were infected. This unexpected result suggested that STBs transmit virus from maternal blood, bathing their surface, to the CTB stem cells adjacent to the villus core. Non-neutralizing anti-viral IgG in primary infection may enhance transcytosis of IgG-coated virions. It is hypothesized that CMV is transmitted from the mother to the placenta and the embryo/fetus by infection of CTB stem cells in floating villi, following transcytosis across the STB barrier, and by infection of invasive CTBs within the uterine wall. The specific aims are: (1) Determine the effects of CMV infection on CTB invasiveness and immune function in vitro and then establish relevance in vivo. 2) Identify/map CMV genes involved in disregulating CTB differentiation/invasion and immune function. (3) Determine whether infection of underlying CTB stem cells near the villus stromal core occurs by transcytosis of IgG-coated CMV virions across the surface layer of STBs in vitro and then establish relevance in vivo. These experiments will advance our knowledge of the role of the placenta in pregnancy complications due to CMV infection, a critical issue in prenatal development. The results could offer the first molecular evidence regarding the route of transmission and lead to strategies to prevent infection of the fetus.

胚胎/胎儿的人类巨细胞病毒（CMV）感染是先天性病毒感染的主要原因。 在美国，这种情况发生在 1% 的活产婴儿中。 其后果包括神经系统发育不良、视力障碍和感音神经性听力损失。 自然流产的患有先天性巨细胞病毒的女性（15%）的胎盘显示出感染证据，但没有胎儿受累，这表明胎盘感染先于病毒传播给胎儿。 成功妊娠取决于正常的胎盘发育，这是一个逐步过程，涉及器官上皮干细胞（称为细胞滋养层）的分化。 CTB 通过两条途径分化成绒毛，绒毛要么将胎盘固定在子宫壁上，要么漂浮在母体血液中。 在第一个途径中，锚定绒毛中的 CTB 开启侵入母体动脉所需的粘附受体和蛋白酶以及引发母体耐受的免疫分子的表达。 我们的研究表明，妊娠早期分化/入侵 CTB 的 CMV 感染在体外下调两种功能重要的阶段特异性抗原非经典 MHC Ib 类 HLA-G 和整合素 α1β1 的表达。 此外，受感染的CTB在体外的侵袭能力显着受损，从体内感染CMV的胎盘中分离出的CTB的侵袭能力也是如此。 侵袭受损和 α1β1 失调之间的这种相关性表明，母体动脉的错误侵袭可能是 CMV 感染胎盘的一个标志。在第二条途径中，CTB 融合形成覆盖浮动绒毛的合体滋养层 (STB)。 当漂浮的绒毛在体外暴露于CMV时，STB未被感染，而下面的CTB干细胞被感染。 这一意想不到的结果表明，STB 将病毒从母体血液中传播到邻近绒毛核心的 CTB 干细胞。原发感染中的非中和性抗病毒 IgG 可能会增强 IgG 包被病毒体的转胞吞作用。 据推测，CMV 通过感染漂浮绒毛中的 CTB 干细胞、跨过 STB 屏障的转胞吞作用以及感染子宫壁内的侵入性 CTB，从母亲传播到胎盘和胚胎/胎儿。 具体目标是：（1）在体外确定CMV感染对CTB侵袭性和免疫功能的影响，然后建立体内相关性。 2) 识别/定位参与失调 CTB 分化/侵袭和免疫功能的 CMV 基因。 (3) 在体外确定绒毛基质核心附近的潜在 CTB 干细胞的感染是否是通过 IgG 包被的 CMV 病毒颗粒跨过 STB 表层的转胞吞作用发生的，然后建立体内相关性。 这些实验将增进我们对胎盘在巨细胞病毒感染引起的妊娠并发症中的作用的认识，巨细胞病毒感染是产前发育的一个关键问题。 研究结果可以提供有关传播途径的第一个分子证据，并制定预防胎儿感染的策略。